Core C will provide investigators of this program project with convenient access to synthetic peptides that are economically produced. Core C provides the instrumentation and expertise for design, synthesis, quality control, and use of synthetic peptides in a shared instrumentation setting. Synthetic peptides are prepared by tBOC and Fmoc chemistries and surplus is reserved for use by other Center investigators. Peptides will be used for mapping monoclonal antibodies, preparing antibodies and identifying peptides derived from chlamydial major outer membrane protein that are presented MHC class II molecules.